Laser-welded butt joints of Ti₂AlNb/42CrMo steel with addition of V interlayer

Welding Ti₂AlNb and 42CrMo steel is important in the field of materials engineering. The formation of Ti–Fe intermetallic compounds upon melting makes it a challenging task due to the significant disparities in the physical properties and chemical compositions of these two materials. An orthogonal experiment was designed and conducted, and crack-free laser-welded butt joints of Ti₂AlNb/42CrMo steel were achieved under optimized parameters. The joints exhibited a tensile strength of approximately 162 MPa. Fracture surface analysis revealed substantial amounts of Fe₂Ti and FeTi intermetallic compounds within the weld zone. According to the principle of element compatibility, a method is proposed for incorporating a partially melted V interlayer for laser butt welding of Ti₂AlNb/V/42CrMo steel. The laser beam was vertically incident on the interface between Ti₂AlNb and V, as well as the interface between V and steel. No visible microcracks were observed after welding. Elemental analysis results indicated that the V interlayer prevented the formation of the Fe–Ti mixed zone. Furthermore, the weld zone primarily consisted of (Fe, V) solid solution and (β-Ti, V) solid solution; thus, Ti–Fe intermetallic compounds were not formed. The tensile strength of the joint reached 572 MPa, and the joint fractured within the unmelted V layer, exhibiting a typical ductile fracture morphology.